The evolution of the third generation (Third Generation, hereinafter referred to as 3G) air interface technologies, such as downlink multiple input multiple output (Multiple Input Multiple Output, hereinafter referred to as MIMO), downlink 64 quadrature amplitude modulation (Quadrature Amplitude Modulation, hereinafter referred to as QAM), and uplink 16QAM, significantly improves the transmission rate of the air interface, and doubles the throughput of the packet switching (Packet Switching, hereinafter referred to as PS) service. As a result, service general packet radio service support nodes (Serving General Packet Radio Service Support Nodes, hereinafter referred to as SGSNs), gateway general packet radio service support nodes (Gateway General Packet Radio Service Support Nodes, hereinafter referred to as GGSNs), value added services (Value Added Services, hereinafter referred to as VASs), and the transmission bearers among these nodes encounter an unprecedented pressure, and particularly, rich Internet services raise higher requirements for the transmission bandwidth of the core network (Core Network, hereinafter referred to as CN), causing that the cost of capacity expansion increases rapidly. The Internet services occupy a large number of transmission resources of mobile operation networks but bring lower profits for mobile operators, and in addition, when users access the Internet services of the packet data network (Packet Data Network, hereinafter referred to as PDN), the packet flow passes through numerous nodes of the core network, and transmission efficiency is quite low. Therefore, currently the operators are eager to seek a suitable solution, where the nodes near the access side directly route the uplink Internet service flow to the PDN network at low cost, and on contrary, the downlink traffic flow is also directly routed from the PDN network to the access side, so as to offload the data flow of the core network.
In the prior art, that a traffic offload function (Traffic Offload Function, hereinafter referred to as TOF) entity for offloading a user data flow is added between a radio network controller (Radio Network Controller, hereinafter referred to as RNC) and an SGSN is proposed, where the TOF entity may be deployed on an Iu-PS interface between a universal mobile telecommunication system (Universal Mobile Telecommunication System, hereinafter referred to as UMTS) network RNC or home Node B gateway (Home NodeB Gateway, hereinafter referred to as HNB GW) and the SGSN. The TOF entity provides a standard Iu interface towards the RNC/HNB GW and towards the SGSN, and completes the traffic offload function through the Gi interface.
However, the prior art only supports the continuity of offloaded traffic of a mobile user equipment (User Equipment, hereinafter referred to as UE) under a same TOF entity, but does not support the continuity of offloaded traffic of a mobile UE across different TOF entities. Furthermore, in some scenarios, the prior art has problems, for example, the TOF entity is unable to obtain user information.